There are lots of reports on the Sudhian Forum that the poor quality of the SATA cables causes the shuttle to crash (apparently they have improved the quality on later versions). The document here recommends replacing the cables.
At first I did not have any problems so I did not do anything, but after a few months some crashes started happening especially during boot up, so I thought I had better do something about it.
It seems to me that the 90 degree cable headers might contribute to the problem (although the power lead seems even worse). The cables have to be bent very tightly and are in contact with the metal frame. It seems to me that this could work the connector loose, especially since the frame is not very rigid due to its tool free construction.
I therefore ordered straight 45cm cables from here because I'm in the UK and because they also sell Bios Savior which I wanted for this project. I do not need cables that light up in ultraviolet light or anything like that, these ones seemed reasonably ordinary:
I traced the original blue cables to where they connect to the motherboard, unplugged them and plugged in the new cables: